1) Isolation, structure determination by single crystal X-ray diffraction, and NMR of siderophores and ferrisiderophores from the iron-deficient media of fungi and bacteria pathogenic to man, insects and plants, as well as siderophores from mycorrhyzal and nitrogen fixing species. 2) Identification, isolation, purification, crystallization and structure determination (X-ray) of the ferrisiderophore receptor protein in Aspergillus ochraceous or the 81 K M.W. ferric enterobactin receptor protein in E. coli K 12. 3) Kinetics and mechanism of ferrisiderophores-uptake in microorganisms from which they are produced. 4) Molecular mechanics calculations to investigate the absolute configuration of siderophores and the flexibility of cyclic peptides. 5) Synthesis of several selected self-duplexing nucleotides and the structure determination by X-ray and NMR of these nucleotides and their complex with a double intercalating agent.